Charge-state distribution of aerosolized nanoparticles

TL;DR

This study introduces a method to detect and analyze the charge-state distribution of aerosolized nanoparticles, which is crucial for improving sample uniformity in single particle imaging experiments using free-electron lasers.

Contribution

The paper presents a novel deflection technique combined with microscopy and simulations to characterize charge states of aerosolized nanoparticles without intentional charging.

Findings

Charge distribution is skewed, consistent with triboelectric charging.

Aerosolized polystyrene particles exhibit spontaneous charging.

Method enables non-invasive charge state detection.

Abstract

In single particle imaging experiments, beams of individual nanoparticles are exposed to intense pulses of x-rays from free-electron lasers to record diffraction patterns of single, isolated molecules. The reconstruction for structure determination relies on signal from many identical particles. Therefore, well-defined-sample delivery conditions are desired in order to achieve sample uniformity, including avoidance of charge polydispersity. We have observed charging of 220 nm polystyrene particles in an aerosol beam created by a gas-dynamic virtual nozzle focusing technique, without intentional charging of the nanoparticles. Here, we present a deflection method for detecting and characterizing the charge states of a beam of aerosolized nanoparticles. Our analysis of the observed charge-state distribution using optical light-sheet localization microscopy and quantitative particle trajectory simulations is consistent with previous descriptions of skewed charging probabilities of triboelectrically charged nanoparticles.